Method for culturing plant materials as foods

ABSTRACT

An incubator apparatus (10) for preparing an aerobically cultured plant material, such as a soyfood substrate (11), inoculated with a beneficial microorganism to form a cultured food, such as Tempeh, is described. The incubator apparatus is comprised of a water tray (13), which provides a water bath (15) for heating the inoculated soyfood substrate loaded in shallow metal trays (45), preferably stainless steel trays. The trays are then supported on tray racks (43) that are mounted in the water bath so that the trays are partially immersed in the water bath. The trays holding the inoculated soyfood substrate are then sealed in the water bath by a cover (61). The cover mounts over the tray racks and is partially immersed in the water bath to seal the cover over and around the trays filled with the inoculated soyfood substrate. An aerating supply system (31) provides for the aerobic culturing of the soyfood substrate while a circulating pump (100) provides a uniform distribution of the water bath throughout the water tray. A sensor (132) and a controller (104) actuate a temperature control system to effect heating and cooling of the water bath as needed to promote the growth of the microorganisms on the soyfood substrate. Later, a heating system (17) is used to elevate the temperature of the water bath to stop the culturing process by killing the microorganisms and to pasteurize the cultured food. The cultured food is then cooled and removed from the trays as a ready to eat food that can serve as an alternative to meat. The Tempeh is high in protein content and high in fiber without having cholesterol.

This is a divisional of copending application Ser. No. 07/871,065 filedon Apr. 20, 1992, now U.S. Pat. No. 5,228,396.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to an incubator apparatus and a method forpreparing an aerobically cultured food from a plant material. Inparticular, the present invention relates to an incubator apparatus anda method for aerobically culturing a plant material, primarily soybeans,provided with a beneficial microorganism, preferably a fungus of thegenus Rhizopus, to prepare a Tempeh. The soybean can also be extendedwith a portion of barley cereal grain or other cereal grains.

The incubator apparatus is comprised of a container for a water bath. Awater circulation means having a sensor controlled heater coil as afirst heater means warms the water bath during the first half of theincubating process and causes the water bath to flow throughout thecontainer. This helps to maintain; uniformity of temperature in thewater bath while the plant material is being aerobically cultured toform the Tempeh. The sensor also controls the cooling of the water bathduring the second half of the incubation process. A second heater meansis mounted in the container for heating the water bath to a hightemperature.

To prepare the Tempeh, shallow metal trays, preferably made of stainlesssteel, are filled with the plant material and supported on racks so thatthe trays are partially immersed in the water bath. The trays arepreferably arranged side-by-side on the racks as units and a pluralityof racks are mounted in parallel in the water bath. The trays can be ofvarious sizes, although it is preferred that they have a depth of about1 inch (2.54 cm) and the plant material is provided in the trays up to adepth of about 0.75 inches (1.9 cm). A removeable lid or cover mountsover and around the trays filled with the plant material. The cover canbe a single, continuous member covering all of the tray units in thewater bath, or there can be individual covers, preferably for eachside-by-side tray unit. A lower rim portion of the cover is immersed inthe water bath to seal the cover over and around the trays. An aeratingmeans is centrally located in the water bath between each side-by-sidetray unit so that an airflow bubbles up through the water bath and movesover the plant material held in the trays. The airflow exits throughperforations provided in the cover, away from the aerating means. Duringthe culturing process, the microorganisms aerobically grow to produceenzymes that act on the proteins, carbohydrates and the oil in the plantmaterial. Tempeh produced in the incubator apparatus is a palatable andnutritious food that can be eaten as is or further prepared by cooking.

After the microorganisms have cultured the plant material, the secondheater means is used to elevate the temperature of the water bath beyondthat which is suitable for growth of the microorganisms. This kills themicroorganisms and pasteurizes the plant material. The trays are thenuncovered to cool the cultured food, and the cultured food is cut intouseable portions and packaged for later consumption.

(2) Prior Art

For centuries in Asiatic cultures and particularly in Indonesia, Tempehhas been a valuable and important food produce prepared by fermentingand culturing whole dehulled soybeans or soybean grits or meal with purecultures of beneficial fungi or microorganisms. Tempeh is an importantfood in Asiatic cultures because soybeans grow readily in moderateclimates and because soybeans contain proteins, carbohydrates, fats,vitamins and other nutrients, but have no cholesterol.

Historically, Tempeh is prepared in small scale operations by firstsoaking whole soybeans in water. The soaked, wet soybeans are thendehulled and boiled in water to soften the beans and destroy anycontaminating microorganisms. The cooked soybeans are then spread out inthin layers to allow the water to drain and evaporate from the surfaceof the soybeans. The air dried soybeans are then mixed with a startercomprising portions of old Tempeh containing a mixture of molds,bacterial and other microorganisms. The moist inoculated soybeans arethen wrapped tightly in banana leaves and the material is allowed toculture at room temperature until the soybeans are completely molded.This product is known as Tempeh, which can be eaten as is or sliced intothin slices, dipped into a salt solution and fried in a vegetable oil.

The culturing of soybeans destroys the bad odor and bad flavor ofsoybeans by apparently causing the microorganisms to produce enzymesthat act on the proteins, carbohydrates and the oil in the soybeans tomake the Tempeh palatable and nutritious and to give a desirable flavor.The microorganisms mainly responsible for Tempeh culturing are stated tobe Rhizopus oryzae and Aspergillus oryzae. These microorganisms requireaeration for growth and the formation of enzymes.

The prior art culturing of soybeans to make Tempeh has numerousobjectionable steps. Since the microorganisms responsible for Tempeh areaerobic, during the culturing process the soybeans must be spread out inlayers that are relatively shallow in depth. This means that the area ofthe soybean layers must be large. Thus, the use of large area trays hasproliferated in recent times for commercial production of Tempeh.Martinelli and Hesseltine (1964) Food Technology, Vol. 18, No. 5 foundthat large metal trays were excellent for commercial Tempeh productionbecause they were more sanitary and allowed for easier removal of theTempeh from the container in comparison to wooden trays (unless thewooden trays were lined with perforated plastic sheeting). The metaltrays were reported to preferably be large aluminum trays instead oflarge stainless steel trays. However, the use of aluminum in prolongedcontact with food is being questioned in relation to its possibleimplication in causing Alzheimer disease. Since stainless steel is apoor heat conductor, having less than 10 percent of the thermalconductivity of aluminum, there tends to be a build-up of heat at thecenter of the tray that causes spoilage there. Plastic school lunchtrays can also be used as Tempeh containers if the tray material isapproved for contact with fermenting foods.

In the prior art methods, the layers of soybeans must also be covered bysome film. The use of banana leaves is extremely primitive, can causecontamination and is limited to those areas tropic enough to supportgrowth of banana trees. More recently, Martinelli and Hesseltine (1964),discussed previously, have suggested the use of a thin sheet ofpolyethylene film, which is perforated every 2 to 3 inches with a nail.The soybeans can also be covered with a reusable sheet of strongerpolyethylene, rigid Plexiglas® or an imperforated sheet of wax paper.

Using an inoculum consisting of a portion of old Tempeh is veryunsanitary. The old Tempeh can be contaminated by a variety of molds,bacteria and yeasts, and this method of preparation is practiced at theexpense of the nutritional benefit of the Tempeh. Also, since theinoculum is highly variable as to the viability of the mold even whenthe inoculum is relatively pure, culturing time requirements for theTempeh are extremely variable, as is the product itself.

The most commonly practiced prior art method of making Tempeh consistsof incubating a layer of soybeans covered with a flexible plastic sheetmodified with aeration perforations. The incubation process takes placein an incubation room having an agitated airflow that is uniformlyheated or cooled and with a consistent humidity. The problem is thatagitation of the airflow often leads to blackened areas on the Tempehwhere the airflow meets the microorganisms at the perforated holes. Thiscontact with the fast moving airflow causes the microorganisms tosporulate prematurely and produces undesirable black spores. The greaterthe agitation of the airflow to ensure that the air in the incubationroom does not stratify, the greater the occurrences of prematuresporulation. Furthermore, it is difficult to accurately control thehumidity in the incubation rooms. If the airflow is slightly drier thanoptimum, the black spore problem is increased. There is thus a need forTempeh and other fermented foods having a more uniform appearance anduseful shape (most of the Tempeh produced today is incubated in 8 ounceperforated plastic bags). There is also a need for the Tempeh to bepasteurized and ready to be consumed.

U.S. Pat. No. 3,228,773 to Hesseltine et al describes an improved methodof preparing Tempeh by fermenting soybeans with certain phycomycetousfungi of the order Mucorales, genus Rhizopus. The soybeans are soakedovernight, the seed coats are removed and the whole soybeans may becracked into large grits. The soybeans are then softened and moistenedby soaking in water and then boiled to sterilize and further soften thesoybeans. Excess water is drained and the soybeans are cooled below 104°F. (40° C.) and then inoculated with a spore suspension of Rhizopusspores. Species of this genus which are operative to give acceptableresults include Rhizopus oligosporus, R. arrhius, R. achlamydosporus, R.formosaensis, R. stolonifer and R. oryzae. The soybeans are thencultured at a temperature of between 77° and 99° (25° to 37° C.). Thesoybeans are cultured in conventional non-toxic, plastic bags modifiedby the presence of 0.02 inch diameter perforations located not over 0.5inches apart. The soybeans are also described as being cultured inperforated flexible, plastic tubing having a diameter of 3.5 inches (9cm). In either example, the resulting Tempeh must be removed from theplastic container and then cooked to prepare the Tempeh as a consumablefood. There is a need for Tempeh and other fermented foods which arepasteurized and ready to be consumed as a food.

U.S. Pat. No. 3,243,301 to Hesseltine et al describes a process ofmaking a novel variety of Tempeh, not exclusively from soybeans. Thenovel Tempeh is made by subjecting cereal grains such as wheat, rye,rice, barley and oats or mixtures of the same, alone or in combinationwith pre-treated soybean grits, to the action of the mold Rhizopusoligosporus. This mold is characterized by the presence of large amountsof both proteolytic and lipolytic enzymes, but little or no amylolyticenzyme. Any appreciable amount of the latter class of enzyme would breakdown the cereal grain starch to simpler sugars that would then befermented to disagreeably tasting organic acids and highly coloredmaterials. Thus, the closely related fungis Rhizopus oryzae and the moldAspergillus oryzae on substrates comprising a cereal grain producedarkly colored, ill-smelling, and unacceptable products.

U.S. Pat. No. 3,981,234 to Nelson et al describes an apparatus for thepreparation of a soybean beverage base. This apparatus produces arelatively coarse ground slurry consisting of water and approximately 12percent by weight of soybean tissue.

U.S. Pat. No. 4,248,141 to Miller, Jr. describes a method and apparatusfor debittering soybeans caused by enzymes lying next to the beansurface directly beneath the skin. The end product is dry, dehulledsoybean halves, suitable for the usual raw soybean use.

Shurtleff & Aoyagi describe the process of making Tempeh in TempehProduction, The Book of Tempeh: Volume II, published by New-Age Foods,1980. Tempeh is L also discussed in Soyfoods, Vegetarian Times, pages 35to 39, Nov. 1987.

Other prior art less directly related to the present invention includesU.S. Pat. Nos. 1,513,174 to Kruger, 4,013,869 to Orts and 4,848,216 toRobau. Kruger describes a grain soaker wherein grain held in the soakercan be immersed in water for a period of time and afterwards raised andpermitted to drain. Orts describes a tortilla warmer and hydrator. Thedevice is particularly useful for warming and hydrating tortillas thathave been cooked at an earlier time and have subsequently become coldand hard. Robau describes a steam-heated milk warmer.

What is needed is a method and an incubator apparatus for the commercialproduction of a pasteurized Tempeh from a plant material, which ispreferably soybeans. The cultured product needs to be produced in aconsistent manner, in a useful shape and be reproducible on a largescale.

OBJECTS

It is therefore an object of the present invention to provide anincubator apparatus for producing a cultured food, particularly Tempehfrom a soybean substrate. Further, it is an object of the presentinvention to provide a method of culturing a plant material to produce aTempeh or other cultured food. Still further, it is an object of thepresent invention to produce a pasteurized food that is suitable forimmediate consumption by an end user. Furthermore, it is an object ofthe present invention to provide an incubator apparatus for producing acultured food, which serves as a good source of protein and calcium, andthat is low in calories and devoid of cholesterol. Finally, it is anobject of the present invention to provide an incubator apparatus thatis relatively inexpensive to build and easy to construct and that isable to produce commercial quantities of a high quality cultured food,which is nutritious and appealing to the taste. These and other objectswill become increasingly apparent by reference to the followingdescriptions and to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a water tray 13 of the incubator apparatus 10of the present invention having a steam line 17, a water inlet line 19and a water outlet line 25.

FIG. 2 is a plan view of the water tray 13 of the incubator apparatus 10of the present invention shown in FIG. 1 and showing two units 47 ofside-by-side trays 45 for holding the soyfood substrate 11 and showing aplurality of covers 61 mounted on tray racks 43 that support the trays45 in the water bath 15 provided by the water tray 13.

FIG. 3 is a left side perspective view of the tray rack 43 that providesfor supporting a pair of side-by-side trays 45 as a unit 47 in the waterbath 15 of the incubator apparatus 10 of the present invention.

FIG. 4 is a left side perspective view of cover 61 mounted on the trayrack 43 to seal the unit 47 of side-by-side trays 45 in the water bath15 of the incubator apparatus 10 of the present invention.

FIG. 5 is a cross-sectional view along line 5--5 of FIG. 2 showing aunit 47 of trays 45 supported in the water bath 15 by the tray rack 43and with the cover 61 sealed around the trays 45 to form the incubatorapparatus 10 of the present invention.

FIG. 6 is a cross-sectional view along line 6--6 of FIG. 2 partiallyshowing a plurality of trays 45 supported in the water bath 15 byrespective tray racks 43 and with respective covers 61 sealed around thetrays 45 to form the incubator apparatus 10 of the present invention.

FIG. 7 is an enlarged view of a portion of FIG. 5 showing the waterinlet line 19B with opening 21 and the water outlet line 25B.

FIG. 7A is an enlarged view of a portion of FIG. 5 showing the wateroutlet line 25D with opening 27.

FIG. 8 is an isometric view of the rotatable end caps 41A and 41B of theair supply system 31.

FIG. 9 is a schematic view of the circulation and automatic temperaturecontrol system for the incubation apparatus shown in FIG. 1 showing thehot water tank 116 and the cold water line 126 controlled by acontroller 104 in response to signals from a sensor 140 mounted in thewater tray 13.

GENERAL DESCRIPTION

The present invention relates to an apparatus adapted for culturing aplant material with a microorganism to produce a cultured food, whichcomprises: an open container means adapted for holding a water bath;shallow tray means with a flat portion surrounded by sides supported inthe container means and holding a quantity of the plant material spreadover the bottom of the tray means, wherein the tray means is mounted inthe container means so as to be partially immersed in the water bath inthe container means with the bottom of the tray means in the water bath;heater means for evenly heating the water bath in the container means;circulation means which evenly regulates the temperature of the waterbath in the container means; aerating means providing an airflow in thecontainer means; and lid means mounted in the container means are sealedover and around the tray means, the lid means having perforations thatprovide for the airflow from the aerating means to move over the plantmaterial held in the tray means and out the lid means, through theperforations to aerate the plant material wherein the heater means andthe circulation means maintain the water bath in the container means ata first water temperature so that the plant material is at a culturingtemperature that is suitable for cultivation of the microorganisms whilethe plant material is being aerated by the airflow from the aeratingmeans to produce the cultured food.

Also, the present invention relates to a method for culturing a plantmaterial with a microorganism to produce a cultured food, whichcomprises: providing a culturing apparatus, which comprises: an opencontainer means adapted for holding a water bath; shallow tray meanswith a flat bottom surrounded by sides and supported in the containermeans and holding a quantity of the plant material spread over thebottom of the tray means, wherein the tray means is mounted in thecontainer means so as to be partially immersed in the water bath in thecontainer means with the bottom of the tray means in the water bath;heater means for evenly heating the water bath in the container means;circulation means which evenly regulates the temperature of the waterbath in the container means; aerating means providing an airflow in thecontainer means; and lid means mounted in the container means and sealedover and around the tray means, the lid means having perforations thatprovide for the airflow from the aerating means to move over the plantmaterial held in the tray means and out the lid means, through theperforations to aerate the plant material held in the tray means;mounting the tray means holding the plant material in the containermeans, partially immersed in the water bath; sealing the lid means overand around the tray means; maintaining the water bath with the heatermeans and circulation means at a first water temperature so that theplant material in the tray means is at a culturing temperature that issuitable for culturing the microorganism with the airflow from theaerating means to produce the cultured food from the plant material;removing the lid means from over and around the tray means; and movingthe tray means from the container means.

The use of the term "plant material" refers to materials of vegetableorigin.

When soybeans provide the plant material, the soybeans are preferablydehulled, soaked, partially precooked, inoculated with beneficial moldmicroorganisms and then filled in shallow metal trays. Barley cerealgrain or other cereal grains can also be added to the soybeans as anextender. This mixture is then cultured by partially submersing thetrays in a heated water bath under aerobic conditions. The water bathprovides for even heating or cooling and uniform culturing of the moldon the soybeans over the entire area of the tray. This provides for theinoculated soybeans to be evenly cultured throughout the areal extent ofthe soybeans in the shallow metal trays, which is important in order tosustain a large scale, commercial production facility. After thesoybeans are finished culturing to form the Tempeh, the mold is killedby elevating the temperature of the water bath above that which the moldmicroorganisms are viable. This also serves to pasteurize the Tempeh,which can then be sectioned into useable portions, packaged and suppliedto end users. Since the Tempeh has previously been pasteurized duringthe mold killing step, the Tempeh can be consumed as is or incorporatedinto other dishes, serving as a nutritious, cholesterol free alternativeto meat.

SPECIFIC DESCRIPTION

FIGS. 1 to 7 show the preferred incubator apparatus 10 of the presentinvention for aerobically culturing a plant material such as a soyfoodsubstrate 11 (FIGS. 5 and 6) so that the soyfood substrate 11 culturesto form a Tempeh.

The following Example is illustrative of the procedure for producing thesoyfood substrate 11.

EXAMPLE 1

In this culturing process, dehulled, whole bean halves of corsoy varietysoybeans were used. The soybean halves were soaked overnight in tapwater heated to the boiling point, 212° F. (100° C.), then allowed tocool to room temperature. About 4.73 liters (1.25 gallons) of Water Wasused for every 1,000 grams (2.2 pounds) of soybean material. The soakingwater was discarded and the soybeans were then boiled without pressurein excess water for 45 minutes. The water was drained, and the soybeanhalves were put into a stainless steel mixer and stirred until they cameto room temperature, 860 grams (1.89 pounds) of vinegar were added whilethe soybeans were mixing. The soybeans were now swollen and soft. Thenthe soybeans were inoculated with spores of the mold Rhizopusoligosporus, which were slowly added from a shaker.

The whole soybean halves can be produced by cracking the beans andblowing off the hulls, or the soybeans halves can be purchased from awholesaler such as Strayer Seed Farm, Inc., Hudson, Iowa. The moldculture can be obtained from Gem Cultures, Fort Bragg, Calif.

EXAMPLE 2

The soybeans were soaked and boiled as in Example 1 and then combinedwith 159 grams (0.35 pounds) of barley cereal grain for every 1,000grams (2.2 pounds) of soybeans. The pearled barley is added 28 minutesbefore the end of the cooking period of the soybeans. This combinationis thoroughly mixed with vinegar added and then inoculated with the moldRhizopus oligosporus as previously described in Example 1. The barleycereal grain can be obtained from wholesalers such as Daily Grind, AnnArbor, Mich.

The apparatus for fermenting the soybeans of Examples 1 and 2 shown inFIGS. 1 and 2, the incubator apparatus 10 is comprised of a water tray13 filled with water 15 (FIGS. 5 and 6) to provide a water bath andhaving a generally rectangular shape in plan view. The water tray 13 ispreferably supported above ground level by leg supports (not shown) andincludes spaced apart sidewalls 13A and 13B extending upwards from abase wall 13C with opposed end walls 13D and 13E between the sidewalls13A and 13B. Right angled extensions 13F and 13G extend horizontallyoutward from the upper end of sidewalls 13A and 13B (FIG. 5) andsimilarly, right angled extensions 13H and 13I extend horizontallyoutward from the upper end of end walls 13D and 13E. The extensionmembers 13F, 13G, 13H and 13I serve as a ledge or mantle around theouter periphery of the water tray 13. Preferably, the water tray 13 ismade of a metal material, such as stainless steel or a galvanized metalthat will not rust and that is easily cleaned and sanitized. The watertray 13 can also be made of a plastic material, or even wood lined witha metal or plastic liner.

As shown in FIGS. 1 and 2, the water tray 13 is provided with a steamline 17, that is U-shaped in plan view. An inlet side 17A of the steamline 17 is connected to a steam source (not shown) upstream from thepoint where the steam line 17 enters the water tray 13 through the endwall 13D, adjacent to sidewall 13B. A downstream portion 17B extendssubstantially the length of the sidewall 13B to a lateral portion 17Cthat extends partially along the end wall 13E. The lateral portion 17Cleads to a return portion 17D that extends along the length of theopposed sidewall 13A and exits the end wall 13D, adjacent the sidewall13A. The return portion 17D then leads to an outlet side 17E thatconnects back to the steam source. The steam line 17 is preferablyprovided with a manually operated valve (not shown) for introducingsteam into the steam line 17. This serves to raise the temperature ofthe water bath to about 175° F. (79.4° C.) to stop the culturing processby killing the Rhizopus oligosporus microorganisms and to pasteurize theTempeh, as will be explained hereinafter. The steam line 17 ispreferably made of stainless steel tubing, although any other conduitmaterial that does not deteriorate when exposed to steam is suitable. Itshould be understood that although the stainless steel steam line 17 ispreferred as the heating means, the heating means could also be providedby an electrical heating coil (not shown) or some other suitable heatingdevice.

As shown in FIGS. 1 and 2, a water inlet line 19 having an inlet end 19Aenters the water tray 13 through the end wall 13D. The water inlet line19 has a perforated section 19B having openings 21 and extends along thesidewall 13B to an end cap 23. The inlet end 19A of water inlet line 19is connected to the pressure side of a pump 100, which is shown in theschematic in FIG. 9 and provides a circulation means for moving waterthrough the openings 21 in the perforated section 19B and into the waterbath 15. As represented in cross-section in FIG. 7, the openings 21 arelocated at approximately the nine o'clock position when viewed along thelength of the perforated section 19B from the inlet end 19A to the endcap 23. Preferably, the openings 21 are spaced at uniform intervals toprovide one (1) opening 21 per tray 45 position along the length of theperforated section 19B of the water inlet line 19, as will behereinafter described in detail.

FIGS. 1 and 2 also show a water outlet line 25 that serves for drawingwater out of the water tray 13. The water outlet line 25 has an outletend 25A that exits the water tray 13 through the end wall 13D, directlyadjacent to the sidewall 13B and that connects to the pump 100 (FIG. 9)tied in with the water inlet line 19. A first imperforate section 25Bextends from the outlet end 25A and along the sidewall 13B to a secondimperforate section 25C extending along the end wall 13E. In thisposition, the first imperforate section 25B is between the sidewall 13Bof water tray 13 and the perforated section 19B of the water inlet line19. The second imperforate section 25C leads to a perforated section 25Dhaving openings 27 (FIG. 7A) spaced at regular intervals along thelength of the section 25D. The perforated section 25D terminates at anend cap 29, adjacent to the end wall 13D. The outlet end 25A of thewater outlet line 25 is connected to the vacuum side of the pump 100(FIG. 9), which as previously mentioned is also connected to the waterinlet line 19 so that water drawn out of the water tray 13 through thewater outlet line 25 is recirculated into the water bath 15 through thewater inlet line 19. Preferably, this circulation is continuous. Afilter (not shown) can also be connected to the pump 100 for filteringthe water before it is recirculated back into the water bath 15,although this is not necessary to practice the full scope of the presentinvention.

As represented in cross-section in FIG. 7, the water outlet line 25 isprovided with openings 27 along the length of the perforated section25D. As viewed along the perforated section 25D from the end cap 29 tothe imperforate section 25C, the openings 27 are located atapproximately the three o'clock position and are spaced at uniformintervals to provide one (1) opening 27 per tray 45 position along thelength of the perforated section 25D of line 25, as will be hereinafterdescribed in detail. That way, the perforated section 19B of the waterinlet line 19 serves to direct the water bath 15 across the width of thewater tray 13 from sidewall 13B to the perforated section 25D mountednext to the sidewall 13A. This serves to maintain the water bath 15 in awell circulated condition so that the temperature of the water bath 15is uniform around the areal extent of the water tray 13. Both the waterinlet line 19 and the water outlet line 25 are preferably made of coppertubing although any other conduit material that does not deterioratewhen exposed to heated water and that is easily cleaned is suitable forpracticing the full scope of the present invention.

FIG. 9 is a schematic view of the temperature control for the water bath15. The water inlet line 19 leads from the pressure side of pump 100 tothe inlet end 19A, which enters the water tray 13 through the end wall13D. The outlet end 25A of the water outlet line 25 exits the water tray13 through the end wall 13D, directly adjacent to the sidewall 13B, andconnects to the suction side of the pump 100. The pump 100 is driven bya motor 102. The pump 100 preferably runs continuously so that water isalways circulating through the water bath 15.

A spring return solenoid valve 106 is mounted in the water inlet line 19and is actuated by the controller 104 through cable 108. Other types ofautomatically controlled valves are also contemplated by the scope ofthe present invention. The solenoid valve 106 is connected to a waterline 110 leading to a water tank 112 provided with a heater coil 114.The water tank 112 has a temperature control mechanism 116 that servesas a dial so that the temperature of the water in the water tank 112 canbe set at a desired temperature. An outlet line 118 leads from the watertank 112 and connects into the water inlet line 19 leading into thewater tray 13.

A cold water line 120 leading from a cold water source (not shown) leadsto a T-connection that branches into a first cold water line 122 and asecond cold water line 124. Cold water line 122 has an inline springreturn solenoid valve 126 connected to controller 104 by cable 128. Thecold water source preferably provides water having a temperature ofabout 40° F. (4.4° C.). As will be explained hereinafter in detail, thesecond half of the culturing process of the soyfood substrate 11 is anexothermic reaction which creates heat that raises the temperature ofthe water bath 15. Thus, the cold water line 122 is used to trickle asmall quantity of cooling water into the water tray 13 in response to asensor 132 in the water bath 15. The sensor 132 sends signals to thecontroller 104 via cable 134 so that the controller 104 operates thevalve 126 to regulate the trickle of cooling water flowing through thecold water line 122 into the water inlet line 19 and into the water tray13. This way, the temperature of the water bath 15 in the water tray 13can be controlled within a strict temperature range to provide anoptimum temperature in the incubator apparatus 10 during the culturingprocess.

The second cold water line 124 is provided with a manually operatedvalve 130 that enables relatively large quantities of cold water to bepiped into the water bath 15 in the water tray 13. This is used to coolthe temperature of the water bath 15 after it has; been raised above140° F. (60° C.) to kill the Rhizopus oligosporus microorganism and topasteurize the Tempeh, as will be described hereinafter. As shown inFIG. 9, the second cold water line 124 is also used to bring the levelof the water bath 15 in the water tray 13 to the proper level (justexiting a drain line 30 provided on the water tray 13).

FIGS. 1 and 2 further show an air supply system 31 comprised of a mainair inlet line 33 entering the water tray 13 through the end wall 13D,adjacent to the sidewall 13A, and having an inlet end 33A connected toan air pump (not shown). The air pump can be provided with an airfilter, if desired. The main air inlet line 33 extends about half thedistance along the length of the sidewall 13A where it connects into afirst manifold 35 that separates into spaced apart lateral open ends 35Aand 35B. The lateral open ends 35A and 35B of manifold 35 are positionedabout one-quarter and three-quarters of the distance along the length ofthe water tray 13, respectively. Both lateral open ends 35A and 35B ofthe first manifold 35 in turn connect into a second manifold 37 thatdiverges into seven tail lines 39, spaced at equal distances along thelength of the second manifold 37. Each of the tail lines 39 in turnconnect to fittings 41 having spaced apart rotatable end caps 41A and41B (FIG. 8) having off center openings 41C (FIG. 6) that serve asadjustable air outlets for bubbling air through the water bath 15. Byrotating the end caps 41A and 41B, the off center openings 41C can bepositioned so that the trail of airflow from the end caps 41A and 41Bcan be adjusted. That way, the air supply system 31 provides part of theaerating system for aerobically culturing the inoculated soyfoodsubstrate 11 to form a Tempeh, as will hereinafter be described indetail. The conduits forming the various portions of the aerating system31 are preferably made of polyvinyl chloride (PVC) tubing, although anyother conduit material that does not deteriorate when exposed to heatedwater and air and that is easily cleaned is suitable for practicing thefull scope of the present invention.

As shown in FIGS. 2 and 3, tray racks 43 are removeably mounted in thewater tray 13 and serve to support a pair of side-by-side trays 45partially immersed in the water bath 15. One tray rack 43 along with theside-by-side trays 45 are referred to as a tray cell or unit 47. Asparticularly shown in FIG. 3, the tray rack 43 is comprised of spacedapart leg members 49, 51A, 51B and 53 connected to opposed rail members55 and 57. The end leg members 49 and 53 have an elongate U-shape whilethe middle legs 51A and 51B are L-shaped members. The opposed railmembers 55 and 57 are formed from right-angle irons having L-shapedcross-sections. The rails 55 and 57 are mounted on the inside of thelegs 49, 51A, 51B and 53 so that the base portions 55A and 57A of therails 55 and 57 extend inwardly along a horizontal plane towards eachother. The end legs 49 and 53 are mounted at the opposed ends of therails 55 and 57, while the middle legs 51A and 51B are mounted at amid-point along the length of the rails 55 and 57 and serve as middlebraces for the tray rack 43. In this position, the upstanding portions49A, 51C, 51D and 53A of the legs 49, 51A, 51B and 53 extend above thevertical sides 55B and 57B of the rails 55 and 57 (FIGS. 5 and 6).

As further shown in FIGS. 2 and 3, an aerating guide 59 completes thetray rack 43. The aerating guide 59 has an elongate, rectangular shapecomprised of spaced apart sides 59A and 59B joined by opposed ends 59Cand 59D with an open top and an open bottom. The aerating guide 59connects between the rails 55 and 57 at a mid-point along their lengthswith the opposed ends 59C and 59D mounted on the inner edges of the baseportions 55A and 57A of the rails 55 and 57. In this position, theaerating guide 59 is mounted between the middle legs 51A and 51B. Asshown in side view in FIG. 5, when the tray rack 43 is mounted in thewater tray 13, the aerating guide 59 is positioned directly above therotatable end caps 41A and 41B of the air supply system and has a lowerportion submerged in the water bath 15.

As shown in FIGS. 5 and 6, when the trays 45 are supported on the trayracks 43, which in turn are mounted in the water tray 13, the trays 45are partially immersed in the water bath 15. This enables thetemperature of the inoculated soyfood substrate 11 held by the tray 45to be regulated during the culturing process by regulating thetemperature of the water bath 15. Approximately the first half of theculturing process is endothermic (requires the absorption of heat). Thisis accomplished by heating the water bath 15 with heated water from thewater tank 112. To introduce heated water into the water tray 13, thesolenoid valve 106 opens the water line 110 in response to the sensor132 and the controller 104. The pump 100 then moves the heated waterfrom water tank 112, through water line 118 and into the water inletline 19 exiting the water tray 13. Approximately the second half of theculturing of the soyfood substrate 11 is an exothermic process and thereleased heat will raise the temperature of the water bath 15. Thus, asufficient amount of cooling water at 40° F. (4.4° C.) is trickled intothe water bath 15 from the cold water source, as previously explained,to maintain the temperature of the water bath at between about 85° F.and 95° F. (29.4° C. and 35.0° C.) with a preferred temperature at about89° F. (32° C.). To ensure that the inoculated soyfood substrate isevenly heated by the water bath 15, the trays 45 are open receptacleshaving a rectangular shape in plan view with a flat bottom 45A and a lowrim 45B. This gives the trays 45 a depth of approximately one inch (2.54cm).

When a pair of the trays 45 are mounted on the tray rack 43 to form atray unit 47, the aerating guide 59 is positioned between theside-by-side trays 45. Furthermore, when the tray unit 47 is supportedin the water bath 15 (FIG. 2), the aerating guide 59 is positioneddirectly above the rotatable end caps 41A and 41B of the air supplysystem 31 with a lower portion of the aerating guide 59 immersed in thewater bath 15. Also, the water bath 15 extends up the rim 45B of thetrays 45 to just below the upper edge of the rim 45B. That way, thetrays 45 are immersed in the water bath 15 for uniformly heating orcooling the inoculated soyfood substrate 11 held by the trays 45. Thetrays 45 are preferably made of stainless steel, although fiberglass,plastic materials and metal materials such as aluminum and steel arecontemplated by the scope of the present invention, as long as they areapproved for contact with food.

During the culturing process, a pair of trays 45 are filled with theinoculated soyfood substrate 11, as shown in FIGS. 5 and 6 and aremounted on the tray rack 43 to form a tray unit 47. The tray unit 47 isthen mounted in the water tray 13 to heat the inoculated soyfoodsubstrate 11 to the temperature of the water bath 15. Preferably thereare seven (7) tray units 47 comprising fourteen (14) trays 45 aligned inparallel along the length of the water tray 13. The stainless steeltrays 45 are immersed in the water bath 15 to a distance just below theupper edge of the rim 45B. Since stainless steel is a relatively poorheat conductor, this serves to uniformly heat or cool the inoculatedsoyfood substrate 11 over the entire areal extent of the trays 45.

To aid in controlling the temperature of the inoculated soyfoodsubstrate 11, a removeable lid or cover 61 is mounted on each of thetray racks 43 to seal the tray units 47 in the water bath 15. As shownin perspective in FIG. 4, the cover 61 is sized to mount over a singletray unit 47 and is comprised of spaced apart sidewalls 61A and 61Bdepending from a top plate 61C (FIGS. 5 and 6), with opposed end walls61D and 61E between the sidewalls 61A and 61B. The opposed end walls 61Dand 61E are each provided with a pair of openings 63 that serve as airoutlets from the cover 61. The openings 63 and the cover 61 along Withthe air supply system 31 previously described provide a sealed aeratingsystem for aerobically culturing the inoculated soyfood substrate 11 toform the Tempeh.

The cover 61 is further provided with an insulation box 64 that mountson the top plate 61C of the cover 61. The insulation box 65 is comprisedof a top plate 65A having spaced apart sidewalls 65B and 65C dependingfrom the top plate 65A to the top plate 61C of the cover 61 and opposedend walls 65D and 65E extending between the sidewalls 65B and 65C. Thisprovides for mounting an elongate block of insulation 67 inside the box65. That way, the cover 61 along with the insulation 67 serves to retainthe heat generated by the water bath 15 on the inoculated soyfoodsubstrate 11 held in the trays 45, which are supported on the tray rack43 and partially immersed in the water tray 13.

To move the covers 61 off and onto the tray racks 43 mounted in thewater tray 13, a bar 71 is mounted through the eye holes of the handles69 of each of the covers 61. The bar 71 is connected by a chain or othersuitable means to a winch means (not shown) for raising and lowering thecovers 61. This provides a means for accessing the tray racks 43 mountedin the water tray 13 so that the trays 45 holding the inoculated soyfoodsubstrate 11 can be mounted on the tray racks 43 to partially immersethe trays 45 in the water bath 15 and for removing the trays 45 from thetray racks 43.

IN USE

The covers 61 are first removed from the tray racks 43 by the bar 71 andwinch means. The trays 45 have already been loaded with the soyfoodsubstrate 11 to a depth of about 0.5 to 0.75 inches (1.3 to 1.9 cm) andthe soyfood substrate 11 has been inoculated with a beneficial moldculture, preferably Rhizopus oligosporus, as previously described in theExamples. A pair of trays 45 holding the inoculated soyfood substrate 11are then mounted on each of the tray racks 43, which have previouslybeen mounted in the water bath 13.

As shown in FIGS. 5 and 6, in this position, the trays 45 are partiallyimmersed in the water bath 15 so that the level of the water bath 15 isjust below the upper edge of the rims 45B of the trays 45. The covers 61are then remounted on the tray racks 43 and the temperature of the waterbath 15 is regulated by introducing into the water tray 13 heated waterfrom the water tank 116. This serves to bring the temperature of thewater bath to between about 85° F. and 95° F. (29.4° C. and 35.0° C.),with the preferred temperature at about 89° F. (32° C.).

A single cover 61 serves to seal a pair of side-by-side trays 45 in thewater bath 15. In this position, the top plate 61C of the cover 61 issupported on the upstanding portions 49A, 51C, 51D and 53A of the legmembers 49, 51A, 51B and 53 (FIG. 5). This enables the lower edge of thesidewalls 61A and 61B and the end walls 61D and 61E of the cover 61 tobe submerged in the water bath 15 to seal the trays 45 in a closedenvironment under the cover 61. Also in this position, the rotatable endcaps 41A and 41B of the air supply system 31 are positioned so that theairflow from the openings 41C is directly below and vertically in linewith the aerating guide 59 portion of the tray rack 43. As shown in FIG.5, the upper end of the aerating guide 59 is spaced about 0.125 inches(0.32 cm) below the top plate 61C of cover 61. This provides a space forthe airflow from the rotatable end caps 41A and 41B to travel up throughthe aerating guide 59 and over the inoculated soyfood substrate 11 heldin the trays 43. Since the cover 61 is sealed in the water bath 15, theairflow can only escape from the cover 61 through the openings 63 in theend walls 61D and 61E of the cover 61. The insulation box 65 mounted onthe cover 61 also helps to retain the warmth of the water bath 15 on theculturing soyfood substrate 11.

Since the second half of the culturing of the soyfood substrate 11 is anexothermic process that releases heat into the water bath 15, the sensor132 in the water tray 13 is used to signal the controller 104 via cable134 to trickle cooling water from the cold water source into the watertray 13 to maintain the desired temperature of the water bath 15. Thepump 100 has previously been turned on to circulate the warmed waterbath 15 in the water tray 13 through the water inlet line 19 and backout of the water tray 13 through the water outlet line 25, as has beenpreviously discussed. This ensures that the temperature of the waterbath 15 remains uniform throughout the areal extent of the water tray13, which provides for uniformly heating or cooling the soyfoodsubstrate 11 held in the trays 45 supported in the water bath 15 by thetray racks 43. With the water bath 15 at a temperature of about 89° F.(31.7° C.), the temperature of the inoculated soyfood substrate 11 isbetween about 85° to 86° F. (29.4° to 30.0° C.).

The water tray 13 is also provided with the overflow drain line 30 (FIG.9) that drains excess water during the culturing process. This preventsthe trays 45 from floating in the water bath 15 as the water bath 15heats up and expands, and as the cooling water from the cold watersource is trickled into the water tray 13.

The closed cover 61 having the openings 63 along with the air supplysystem 31 comprise an aerating means that along with the regulatedtemperature of the water bath 15 provides an aerobic environment thatpromotes the growth of the Rhizopus oligosporus microorganisms on thesoyfood substrate 11 to form the Tempeh. The Rhizopus oligosporusmicroorganisms also serve as a binding agent to hold the Tempeh togetherand to give the Tempeh a pleasant and meaty texture. Each tray 45 iscapable of producing between about 3 to 6 pounds (1.4 kg to 2.7 kg) ofTempeh in a twenty-three (23) hour period, which is the usual culturingtime for the Rhizopus oligosporus microorganisms. As shown in plan viewin FIGS. 1 and 2, the preferred water bath 15 contains seven (7) trayunits 47 comprising side-by-side trays 45 mounted on a tray rack 43.With all fourteen (14) trays 45 of the tray unit 47 loaded to an optimalweight with the inoculated soyfood substrate 11 as previously described,about 63 pounds (28.6 kg) of Tempeh can be produced in a twenty-three(23) hour period resulting for example in 30 Tempeh patties per tray,each pattie weighing about 2.4 ounces (68.5 grams).

After the inoculated soyfood substrate 11 has fully cultured to form theTempeh, steam is moved through the steam line 17 and is used to raisethe temperature of the water bath 15 to about 175° F. (79.4° C.). Thetemperature of the Tempeh is thereby raised to about 160° F. (71.1° C.).This serves to kill the Rhizopus oligosporus microorganisms and topasteurize the Tempeh. To kill the microorganisms, the temperature ofthe Tempeh must be raised to a minimum of 140° F. (60° C.). If theTempeh is scheduled for incorporation into other foods, which are to beheated above 140° F., this step can be omitted. The winch is thenactuated to enable all of the covers 61 to be simultaneously removedfrom the racks 43 to uncover the trays 45.

It should be understood that while providing the seven (7) parallelcovers 61, each covering a separate tray unit 47 is preferred, a singlelarge cover (not shown) that mounts over all seven (7) tray units 47comprising the fourteen (14) trays 45 supported in the water bath 15 canalso be used. This single, large cover could be removed from the trays45 by the same chain and winch system previously described.

After the temperature of the water bath 15 has been brought to asufficiently high temperature to assure that the temperature of theTempeh has reached at least 140° F. (60° C.), the water bath is againcooled down to 89° F. (31.7° C.) by introducing cooling water at atemperature of 40° F. (4.4° C.) into the water tray 13 from the coldwater source, as previously explained. The trays 45 with the finishedTempeh are then removed from the water bath 15. New trays 45 withinoculated substrate for the next batch of Tempeh are then inserted intothe water bath 15 to begin the culturing process all over again. Thefinished Tempeh is removed from the trays 45 and can be shaped in manyuseful forms such as various sized patties, ribs, strips, cubes andsmall or large grated Tempeh. The number of recipes in which Tempeh canbe used as a food is only limited by the imagination of the preparer.

The nutritional information for a 2 ounce serving of the Tempeh is:

calories-110

protein-12 grams

carbohydrates-8 grams

fat-3 grams (mostly polyunsaturated)

cholesterol-0 grams

sodium-4 milligrams

Also, it is contemplated by the scope of the present invention thatthere can be a plurality of incubator apparatus 10 mounted one above theother in a spaced relationship. That way, a single winch means can beused to mount and remove a plurality of covers 61 from the stackedincubator apparatus 10 at the same time. Also the circulation, heating,cooling and pasteurizing can be controlled by one sensor 132 in eachwater tray 13 of the plurality of incubator apparatus 10. There can bethree water tanks (not shown) in a boiler room, the first tank holding190° F. (87.8° C.) the third tank holding 40° F. (4.4° C.) water. Waterfrom the respective water tanks is then introduced into the water tray13 at the appropriate time in response to the sensor 132 which signalsthe controller 104 to open and close a piping system with valves thatare connected to the pump 100. This would provide economics of scale forcommercial production of Tempeh from the inoculated soyfood substrate11.

Further, it is contemplated by the scope of the present invention thatthe temperature of the water bath 15 in the water tray 13 can beregulated by a single heater means. This can be provided by heating coilwhich can be mounted in the line 17. The electric heating coil can becontrolled by a regulator in response to the sensor 132 to raise thetemperature of the water bath from 90° F. (32.2° C.) to 190° F. (87.8°C.) to stop the culturing process by killing the microorganisms and topasteurize the Tempeh, as has previously been discussed. Also, theheating coil 114 in water tank 112 serves this purpose. When thetemperature of the water bath 15 needs to be lowered to cool the Tempeh,cooling water can be introduced into the water tray 13 from the coldwater source.

It is intended that the foregoing descriptions be only illustrative ofthe present invention and that the present invention be limited only bythe hereinafter appended claims.

I claim:
 1. A method for culturing a plant material with a microorganismto produce a cultured food, which comprises:(a) providing a culturingapparatus, which comprises: an open container means holding a waterbath; shallow tray means with a flat bottom surrounded by sides andsupported in the container means and holding a quantity of the plantmaterial containing added microorganisms spread over the bottom of thetray means, wherein the tray means is mounted in the container means soas to be partially immersed in the water bath in the container meanswith the bottom of the tray means in the water bath; heater means forevenly heating the water bath in the container means; circulating meanswhich evenly regulates the temperature of the water bath in thecontainer means; aerating means providing an airflow in the containermeans; and lid means mounted in the container means and sealed over andaround the tray means, the lid means having perforations that providefor the airflow from the aerating means to move over the plant materialheld in the tray means and out the lid means, through the perforationsto aerate the plant material held in the tray means; (b) mounting thetray means holding the plant material in the container means, partiallyimmersed in the water bath; and (c) sealing the lid means over andaround the tray means; (d) maintaining the water bath with the heatermeans and circulation means at a water temperature so that the plantmaterial in the tray means is at a culturing temperature which incombination with the airflow from the aerating means that is sufficientfor culturing the microorganisms to provide the cultured food from theplant material; (e) removing the lid means from over and around the traymeans; and (f) removing the tray means from the container means.
 2. Themethod of claim 1 wherein the circulating means creates a circulatingflow of the water bath to provide for even distribution of the waterbath throughout the container means.
 3. The method of claim 1 wherein asensor means is mounted in the container means and wherein actuating thesensor means controls the heater means for providing the evenly heatedwater bath in the container means.
 4. The method of claim 3 wherein theheater means is an electric heating coil means controlled by the sensormeans and wherein the sensor means is actuated to cause the heater meansto provide the evenly heated water bath in the container means.
 5. Themethod of claim 1 wherein after the plant material has completedculturing .to form the cultured food, a second heater means is used toelevate the water bath in the container means to a second watertemperature which kills the microorganisms.
 6. The method of claim 5wherein the second heater means is a steam conduit means immersed in thewater bath in the container means and is used to raise the water bath inthe container means to the second water temperature to at leastpasteurizes the cultured food.
 7. The method of claim 5 wherein thetemperature of the water bath in the container means is elevated by thesecond heater means to the second water temperature so that thetemperature of the plant material is above about 140° F. (60° C.) tokill the microorganisms.
 8. The method of claim 1 wherein the heatermeans is an electric heating coil means that regulates the water bathbetween the first water temperature and a second water temperature,which kills the microorganisms.
 9. The method of claim 1 wherein thetray means are removed from the container means after the cultured foodis produced.
 10. The method of claim 1 wherein the microorganisms areselected from the genus Rhizopus.
 11. The method of claim 1 wherein thelid means is provided with insulation means so that when the lid meansis mounted over the tray means, the lid means retains the heat generatedby the heater means in the water bath in the container means to maintainthe plant material at the culturing temperature that is suitable forculturing the microorganisms.
 12. The method of claim 1 wherein thecontainer means is comprised of an elongate, rectangular bottom platehaving opposed sidewalls and end walls between the sidewalls extendingupward from the bottom plate and wherein the lid means is comprised ofan elongate, rectangular top plate with opposed sidewalls depending fromthe top plate and with end walls between the sidewalls of the lid means,and wherein the lid means is mounted in the container means to cover thetray means with the sidewalls and end walls of the lid means partiallyimmersed in the water bath in the container means to seal the lid meansover and around the tray means supported in the container means.
 13. Themethod of claim 1 wherein the plant material is cultured at theculturing temperature of between about 85° F. to 95° F. for betweenabout 21 to 23 hours.
 14. The method of claim 1 wherein the plantmaterial is comprised of soybeans and the cultured food is Tempeh. 15.The method of claim 1 wherein the tray means is supported in thecontainer means on a rack means mounted in the container means, andwherein each rack means supports a unit of side-by-side tray meanspartially immersed in the water bath in the container means, whereinmultiple lid means are provided, one for each unit of the rack means andthe lid means are supported by the rack means and wherein the aeratingmeans is positioned between the side-by-side tray means supported oneach of the rack means, wherein the airflow from the aerating meansmoves over the plant material held in the side-by-side tray means andout through the perforations in the lid means for culturing the plantmaterial held in the tray means to form the cultured food.
 16. Themethod of claim 15 wherein the perforations through the lid means areprovided adjacent to each of the tray means and the air flows from theaerating means and over the plant material held in the tray means toaerobically culture the plant material to form the cultured food. 17.The method of claim 15 wherein there are at least two units of parallel,side-by-side tray means mounted on individual rack means mounted in thecontainer means with individual lid means supported by the rack means tocover each of the units of tray means and wherein each of the individuallid means is provided with a hanger means connectible to a winch meansfor removing the lid means from covering the units of tray means so thatthe tray means can be removed from the container means to remove thecultured food from the tray means and wherein after the culturing iscompleted the lid means are removed by the winch means.
 18. The methodof claim 17 wherein at least two adjacent lid means are linked togetherwith the hanger means and the winch means then removes the two lid meansfrom the two units of side-by-side tray means.
 19. The method of claim 1wherein the tray means are between about 1.3 and 3.8 cm in depth to thebottom and the plant material is filled in the tray means to a depth ofabout 0.6 to 1.9 cm and wherein the plant material is evenly heated bythe tray means partially immersed in the water bath during theculturing.